The BGS Lexicon of Named Rock Units — Result Details
Bryn Brith Member
Computer Code: | BYN | Preferred Map Code: | BnB |
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Status Code: | Full | ||
Age range: | Abereiddian Stage (O2) — Abereiddian Stage (O2) | ||
Lithological Description: | Massive lenticular beds of disturbed mafic tuff, tuffite and tuffaceous sandstone, with subordinate thin mudstones. | ||
Definition of Lower Boundary: | Conformable on the felsic ash-flow tuffs of the Offrwm Volcanic Formation or within the lowermost mudstones of the Cregennen Formation. | ||
Definition of Upper Boundary: | Conformable within the mudstones of the Cregennen Formation. | ||
Thickness: | To 65m, and might be locally up to 150m. | ||
Geographical Limits: | Cadair Idris district. | ||
Parent Unit: | Cregennen Formation (CREN) | ||
Previous Name(s): | Bryn Brith Beds [Obsolete Name and Code: Use BYN]
(-3889)
Bryn Brith Grits (-742) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Type Section | Crags of Bryn Brith. Pratt, W T, Woodhall, D G and Howells, M F. 1995. | ||
Reference(s): | |||
Cox, A H, and Wells, A K. 1921. The Lower Palaeozoic rocks of the Arthog-Dolgellau district (Merionethshire). Quarterly Journal of the Geological Society, London, Vol.76, p. 254-324. | |||
Cox, A H, and Wells, A K. 1927. The geology of the Dolgelley district, Merionethshire. Proceedings of the Geologists' Association, Vol.38, 265-318. | |||
Pratt, W T, Woodhall, D G and Howells, M F. 1995. Geology of the country around Cadair Idris. Memoir of the British Geological Survey, Sheet 149. (England and Wales). (London: HMSO), 111pp | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
E149 |